Morphogenesis of eyelid meibomian gland

Purpose Dysfunction of Meibomian gland is the primary cause of dry eye. The purpose of our study is to understand embryogenesis for a better understanding of the pathophysiology of these diseases. Methods Eyelids were obtained from 22 fetuses formalin fixated of 10‐34 weeks gestational age (GA) with approval of Ethics Committee. These 88 eyelids were processed with sections 5µm thick and analyzed by light microscopy after staining with hematoxylin‐phloxine‐saffron and PAS reaction. For each sample, different morphological criteria were investigated: evaluation of glandular bud, sebaceous gland differentiation, arborization of the gland, opening of excretory duct. Results Histological analysis revealed that up to 13 weeks of GA, the fetal lid consists of fine vascular structures in a loose mesenchyme, under a very thin epithelium. At 14 weeks of GA, a first process of the excretory duct is individualized as a cell invagination extending from the eyelid margin. Sebaceous cell differentiation is identified at 15 weeks of GA. The excretory canal keeps its maturation to appear as a small cellular cord, unique and full around 16 weeks of GA, glands begin its buds arborization at 19 weeks of GA. This channel gradually widens and expands, appearing always blocked by a plug of squamous cells and keratin cuticle at 22 weeks of GA. The plugging lasts until 34 weeks of GA. Conclusion Glandular structures involved in tear secretion appear in fetus around fourteen weeks of gestation. The Meibomian glands extend its maturation after birth. Further studies will allow a better understanding of the physiopathology of dry eye.